Reinforced exhaust valves Subaru SVX 3.3 EG33

Subaru engines covered

The Subaru SVX (CX), sold from 1992 to 1997, uses the EG33, a 3.3 litre 24-valve engine.

The EG33 has 12 exhaust valves. The reinforced valves come in standard size, with a 32 mm head, a 5.96 mm stem, a 90.9 mm overall length and a 4.3 mm tip.

SUPERTECH reinforced exhaust valves

On a naturally aspirated engine, the head of an exhaust valve reaches 760 to 870 °C, and goes beyond 1,000 °C when turbocharged or supercharged. About 75 % of that heat leaves through the seat and 20 % through the guide. EV8 family steel, taken as the reference for the original part, drops from 550 MPa at 600 °C to 300 MPa at 800 °C: the head overheats, fatigues, distorts and eventually stops sealing.

The SEVI-1080-12 is made of Inconel, a nickel based superalloy that keeps 860 MPa at 732 °C and 554 MPa at 816 °C, about 85 % more than EV8 steel around 800 °C.

Exhaust valve technical specifications

Valve fitting

Before reassembly, check that the collets suit the lock groove of the SEVI-1080-12.

In standard size, the SEVI-1080-12 fits exhaust seats cut back to their factory diameter.

The stem tip is 4.3 mm long.

Technical guide

Our brand

SUPERTECH Performance, competition valves designed in California, offers one exhaust valve for the SVX EG33, in Inconel and in standard size.

How to choose

A single reference covers this engine:

When reinforced valves become necessary

• Fitting a supercharger or a turbo (Inconel version recommended)
• More aggressive camshafts
• Sustained track use
• Cylinder head rebuild with worn exhaust valves

Vehicle compatibility

OEM part number (exhaust valve):

Don't forget the inlet valves

When the EG33 cylinder head is off, replace the inlet valves and valve stem seals at the same time.